Apparatus for dehydrating liquid products



May 14, 1946.

J. M. HALL 2,400,458

APPARATUS FOR DEHYDRATING LIQUID PRODUCTS 2 Sheefcs-Sheet 1 OriginalFiled Feb. '7, 1940 fla INVENTOR BY 2Z1 ATTORNEYS.

@sflh MHall Mf May 14, 1946. J. M. HALL APPARATUS FOR DEHYDRATING LIQUIDPRODUCTS Original Filed Feb. 7, 1940 2 Sheets-Sheet 2 bum ' INVENTOR.LESQ D/Z M Hall BY M4 dim 7%;

ATTORNEYS.

Patented May, 1946 PRO Joseph M. Hall, Chicago. in.

& Concentrating Company,

application February 7,

Doors assignor to Drying a corporationof- 1940, Serial No.

ginal 317,720; Divided and this application June 25, v 1942, Serial No.448,380 I 11 Claims. '(01. 159-4) This invention relates to a system ofdesiccating or dehydrating liquid products; and one of the principalobjects of the invention is the provision of a new and. improvedarrangement of the various structures of the system whereby a largeamount of air at atmospheric temperature may be mixed with a quantity ofheated air for forming the dehydrating medium.

Another object of the invention is the provi-, sion of a new andimproved dehydrating system having novel means for dehydrating liquidproducts, and novel means for circulating the drying medium.

A further object of the invention is the provision of a new and improvedmeans for insuring delivery of the dehydrated product from thedehydrator in a continuous process.

Another object of the invention is the utilization of a large portion offresh air in the drying medium without first passing it through aheater.

A further object of the invention is the provision of a new and improvedsystem of dehydrating liquid products wherein fresh air heated by thedischarged drying medium is employed for initially concentrating theproduct.

A still further object of the invention is the provision of a new andimproved evaporator mechanism for utilizing residual heat contained inthe drying medium after dehydrating the 1muid product for preheating thedrying medium for use in both the initial and final steps in theconcentration and dehydration operation.

Another object of the invention is the provision of a new and improvedsystem for dehydrating liquid products employing an apparatus that issimple in construction, eflicient and economical in operation, requiresa minimum of artificial heat, is composed of few parts, and that is notlikely to become deranged or get out of order.

Other and further objects and advantages ofthe invention will appearfrom the following description, taken in connection with theaccompanying drawings, in which- Fig. 1 is a diagrammatic view inelevation of a portion of an apparatus for'dehydrating liquid products;

Fig. 1 is a similar view of the remaining portion of the apparatus; 4

Fig. 2 is a top plan view of a portion of the construction shown in Fig.1; T

Fig. 3 is a section on the line Fig. 4 1; and

Fig. 5 is a section on the line 5-5 of Fig. 1.

In dehydrating liquid products it is common 3-3 of Fi 1;

is a cross-section on the line 4-4 of Fig.

practice to remove the moisture from the product by a heating gaseousmedium, such as air, dry steam, or the like. The present inventionemploys heated air for this purpose. Air-under at- 5 mosphericconditions is usually much below its saturation point, and consequentlyit possesses considerable capacity for absorbing moisture.

, The present invention seeks to take advantage of this fact in theprovision of means for heating only a portion of the air supplied to thedehydrator, and to mix this heated portion with a copious supply oi airunder atmospheric condi-- tions immediately prior to the dehydratingoperation. By means of this arrangement an econ-' oiny in-heat units isobtained due to utilizing such a large number of heat units contained inair under atmospheric conditions. A high rate of evaporation may'beobtained at moderately elevated temperatures of the heating medium ifthe liquid product be atomized and projected into direct contact withthe heating medium while it is moving at high velocity. v

In the resent invention the concentration and dehydration areaccomplished by projecting the atomized liquid product into spirallymoving currents -of moderatelylheated air. The outward and downwardmovement of the liquid particles through the air, together with theircentrifugal movement radially outward in the spirally moving heatedcurrent of air, insures a constantly changing contact of those particlesand air, and such everchanging contact is conducive to a high rate ofevaporation. With this system excellent results may be obtained by theuse of airheated but a few degrees above the boiling point of water, sayfrom 220 to 225 F., although much' higher temperatures may be employed,if desired. The evaporation of the moisture from around the particlesprevents the particles from becoming overheated while they containmoisture. But the evaporation of the moisture quickly lowers thetemperature of the air so that the dried particles do not come incontact with air at temperatures sufficiently high to injuriously affectthe product. Furthermore, the process is of suchshort duration that theparticles are not subjected to heat even at moderately high temperaturesfor but a-few moments.

Referring now to the drawings, the reference character It designates theapparatus which comprises a tank I l for containing the liquid productto be dehydrated; anevaporator or dehydrator chamber or cabinet l2,which, for convenience, I may be termed the first evaporator orevaporator 56 chamber; a second evaporator 01'' dehydrator chamber orcabinet I3, which may be termed the second evaporator; and an evaporatoror dehydra-- tor chamber or cabinet I4, which may be termed the thirdevaporator, in which the liquid product is dehydrated. For conveniencethe chamber I4 tor I4. The liquid product and the drying.

medium pass through the second evaporator and the dehydrator in.opposite directions.

Referring now to Fig. 1, the liquid product contained in the reservoiror container I I is forced by the pump 23 through the conduit 24 intothe first evaporator I2 in the usual manner. The first evaporator I2 isof the centrifugal separator type,

and comprises an upper cylindrical section and a lower tapered section26. The lower end 21 of the tapered portion 28 has its walls at a moreobtuse angle to the axis of the chamber than the remaining part of thetapered portion for shortening the height of the evaporator, as clearlyshown in said figure. The upper part of the cylindrical portion 25 isclosed by the top wall 30, which may have its central part depressed toform an annular upwardly extending portion 28 of the main chamber whichextends above the distributor or spray member 29, as will presentlyappear.

The distributor member 29 is in the form shown in my copendingapplication Serial No. 275,934, filed May 26, 1939, and comprises arotating hollow shaft 3| (Fig. 4) extending axially downwardly throughthe upper portion of the chamber 25, and has attached at its lower end aplurality of arms 40 having nozzles 32 attached thereto. Attached to thearms 48 is an annular deflector member 33, concave on its upper surface.The distributor member 29 is attached to the hollow shaft 3| and isrotated by a motor 34. The arms 40, to which the nozzles 32 areattached, are each provided with a passage 50 in communication with thepassage 60 formed in the hollow shaft 3 I and are shaped to form fanblades, as shown at 40 in Fig. 5, for exhausting air from the chamberI2. The liquid product passes downwardly from the conduit 24 through thehollow rotating shaft 3|, through the passages in the arms 40, and bythe action of centrifugal force it is discharged from the nozzles 32into the evaporator I2 in the form of a spray of finely dividedparticles.

Suitable means are provided for evaporating a portion of the moisturesprayed into the cabinet or chamber. In the form of construction shown,air is employed as the heating and evaporating medium. This air isheated and circulated through the system, including the heat exchangerIS, in a manner that will shortly be described.

The heat exchanger I8 comprises an outer casing 35 having a tapered end36 in communication with the discharge of the fan I5. The casing istapered at its opposite end, and is in communication with a conduit 31.The casing is provided at each end with partitions or flue sheets 38 and39, which are perforated and have tubes or flues 4| secured in theperforations, the tubes forming passages for the air through the heatexchanger. The intake 42 of the fan I5 is provided with suitthe chamber65 able filters 43 so as to clean the fresh air introduced into thesystem and forced by the fan II throughthe heat exchanger I 8. The airintro duced by the fan I 8 is heated in the exchanger by the airexhausted from the second evaporator, as will presently appear.

Mounted within the casing II are a plurality of baflies 44 extendingfrom'opposite sides .of the heat exchanger so as to cause the heated airexhausted from the second evaporator I 3, and introduced through theconduit 45 into the casing 38 at one end thereof, to take a zig-zagcourse through the heat exchanger as it flows around the tubes H and outthrough the discharge conduit 48 at the opposite end of the casing 38,thereby imparting a maximum amount of heat to the air introduced intothe conduit 31 by the fan I5. The air passing through the heat exchangerI8 from the conduit 45 is discharged through a pipe 48 into theatmosphere, after it has imparted heat to theair introduced into theheat exchanger by the fan" I5, or it may be used for other heatingpurposes about the plant.

A portion of the air flowing exchanger I8 from the fan I5 may bediverted by an adjustable valve 310 into the conduit 41, and theremainder is delivered to a snail 48 which discharges the air in aspiral form through the opening 49 into the chamber I2 onto thedeflector 33 across the spray of the liquid product. This heated air,moving spirally downwardly around the walls of the chamber, thenupwardly in an inner spiral, is exhausted by the fan formed by thedistributor 29 through a sleeve or conduit 5| extending axially into thecasing 52, from which it is finally discharged through the conduit 53.The intimate contact between the heated air and atomized particles ofthe liquid product within the first evaporator I2 evaporates aconsiderable portion of the moisture, and the concentrate falls or flowsby gravity to the bottom of said evaporator.

A portion of the air deflected into the conduit 41 by the valve 310 iscaused to flow through the heater I9 01 the furnace I8 into the conduit54 by the fan IT. The furnace I8 comprises the heater or heating chamberI9 and the combustion chamber 29. The heater I9, which is in the upperportion of the furnace I8, comprise a casing 55 provided with the fluesheets or partitions 56 and 51, which are perforated and have tubes orlines 58 secured therein through which air from the fan I I passes tothe conduit 54. The top wall 59 of the combustion chamber is provided atits front end with passages 6| through which the heated gases pass intothe heater I9 about the forward end portions of the tubes 58 for heatingthe air as it passes through said through the heat tubes.

The heater chamber is provided with one or more baiiles 82, one beingshown, which causes the heated combustion gases to take a zig-zag paththerethrough. The rear wall 63 of the combustion chamber is spacedforwardly of the rear wall 64 of the furnace to form a discharge chamber65 for the exhaust gases. In order to conserve heat a portion of thesegases may be recirculated by a fan 66. This fan exhausts from through aconduit 8'! connected with the intake of the fan, and discharges into aconduit 68. This conduit returns the heated gases to the combustionchamber through the front wall 69 of the furnace. The remainder of thegase in the chamber 65 is discharged into the stack through a conduitI2. A valve 13 is upwardly through the snail 48 into the conduit 68,asmay be desired. The air, in pasing through the'heater I9, is heated toa high temperature and is delivered, in this heated condition, throughthe conduit. 54

' to a snail 15 having an outlet into the dehydrator M. The conduit 54may be provided with an air filter 18, if desired. A large volume offresh air, at atmospheric temperature, .is

- adapted to. be mixed with the highly heated air from the furnace l8.In the form of construction selected to illustrate one embodiment of theinvention, the' blower 2| is employed for this v purpose- I The blower2! draws in'fresh air and vdischarges it through the conduit I8 andthrough of conventional design, where it is thoroughly while itstemperature ha been lowered, is still far above its saturation point,and for that reason is employed in concentrating the liquid prodnotafter it leaves the first evaporator." The air passing along the conduit84 from the dehydrator it enters a snail 88, which delivers the air into'the'filter 10 in said conduit, into the snail mixed with the heated airby the gyratory -mo- *tion given the two streams of airby said snail.

The dehydrator i4 is similar to the first evaporator, and comprises anupper portion 11, a

lower tapered portion 18, and a depressed top portion 19. The topportion I9 is provided with an enlarged opening 8|, the walls of whichare integral with the snail l5 .and constitute an outlet for said snail.Extending axially downwardly through theopening 8| and axially of thedehydrator is a sleeve or cylindrical casing 82 of less diameter thanthe opening 8l,:and which is connected at its upper end to, andsupported by, an I enlarged casing 83, which in turn is in communicationwith a conduit 84 leading' to the second evaporator chamber l8.Extending axially downwardly through the casing 83 and sleeve orcylindrical casing 82 is a hollow shaft 85, through which theconcentrated liquid product is delivered to the rotating distributorhead or member 88 beneath the sleeve or casing 82. The shaft 85 isprotected by a sleeve 85 surrounding the same. This shaft is adapted tobe rotated in any suitable manner, as by means of the motor 81.

Since the distributor member or distributor 86 is similar to thedistributor 29 already described, it is not thought necessary to furtherillustrate or describe the same further than to say that the distributoror distributor member, as in the one previously described, functions asan atomizer and as an exhaust fan for removing the air or evaporatingmedium from the chamber l4.

The drying medium passes from the snail I5 into the dehydrator and isdirected across the spray for dehydrating the sprayed particles, as inthe previous construction. This air passes downwardly in a spiral pathto the 1ower portion of the dehydrator and then passes upwardly in aspiral path of smaller diameter, and is exhausted through the casing 82by the spray head 86, the arms of which are constructed to constitute anexhaust fan. These arms are fiattened and turned at an angle to form thefan blades, as shown in Figs. 4 and 5. The dry particles of the productare thrown by centrifugal force against the walls of the cabinet andfall by gravity to the bottom of the cabinet.

The lower end of the deb drator I4 is provided with an upstandingconical member 95. The conical member 95 may be integral with the wallsof the dehydrator and forms with said walls an annular channel orpassage 96. The passage 96 is connected with an outlet passage 91 (Fig.3), which is tangential to the passage 98.

The air discharged from the dehydrator I4,

the second evaporator in a spiral form across the nozzles of the sprayhead 89 for evaporating moisture from the concentrated. liquid product.Since the-construction of the evaporator I9 is sim.. ilar to theevaporator 12 and the parts are similarly arranged and function in alike manner, it is not thought necessarry to repeat the description ofthe same at this point.

The air, after passing spirally downwardly to the lower. portion of thesecond evaporator, and then upwardly in an inner spiral, is exhaustedfrom the evaporator l3 by the distributor 89 into the conduit 45,an'dfrom thence the air passes through the heat exchanger It for heatingfresh air forced through the heat exchangerby the, fan l5, as hasalready been described.

It will thus be seen that the liquid product has,

a portion of its moisture evaporated in the first evaporator, l2 byfresh air which is heated from the' air discharged from the secondevaporator, and that the concentrate which is discharged from the bottomof the first evaporator I2 into a conduit 9.! is forced by the pump 92into the second evaporator l8, where it is further concentrated' in saidevaporator by air discharged from the'dehydrator l4. The concentratefrom the evaporator chamber I8 is caused to flow through a conduit 93 bya pump 94 into the dehydrator M, where it is sprayed into heated airmoving spirally in the dehydrator and dehydratl3. Fresh airis employedin the first evaporator,

but this air is heated by the air discharged from the second evaporator.

In the operation of centrifugal separators there is usually a partialvacuum formed along the axis of'the separator, due to the centrifugalaction of the rotating mass of air. As a result of this phenomenon someof the dried particles may be carried upwardly by the rotating innercolumn of air and are in turn thrown outwardly by the centrifugal forceof the inner column into the outer rotating column, thus starting thecycle all over again.

Suitable means are provided for preventing this recirculation by causingthe particles to be discharged from the cabinet as soon as the aredeposited in the lower-part thereof.- As shown, this is accomplished bycausing a blast of air to be discharged across the outer end of theconduit 91 so as to partially exhaust the air from said conduit byinduction, As shown, this is accomplished by a conduit 98 through whicha current discharged axially from the separator through the conduitlfll, and the material is discharged through a power control valve I02in the lower portion of the separator 22, as is usual in suchconstructions. Since the separator 22 is of the usual or any well knownconstruction, it is not necessary to describe the details oi. the same.I;

It will thus be seen that in this system on a portion of the gaseousdrying medium is heatd, and that the remaining portion of the dryingmedium is introduced directly from the atmosphere.

The product may, if desired, be removed from either the first or secondevaporators through the valves I20 in a more or less concentratedform,as desired.

While the apparatus is described as a mechanism for dehydrating aliquid, it is understood that it is also adapted to be employed indehydrating fluid products of various kinds, as comminuted foods influid state, and the like.

This application is a division of my application for Method of andapparatus for dehyd ting liquid products, filed February 7, 1940, SerialNo.

317,720, which matured in Patent No. 2,290,470, dated July 21, 1942.

It is thought from the foregoing, taken in connection with theaccompanying drawings, that the construction and operation of my devicewill be apparent to those skilled in the art, and that changes in size,shape, proportion and detail may be made without departing from thespirit and scope of the appended claims.

I claim as my invention:

1. In a system for dehydrating a liquid product, a plurality ofevaporator chambers, a heat exchanger, a heater, means for conductingfresh air through said exchanger for preheating said air, a conduit forconducting a portion of said preheated air through said heater tocertain of said evaporator chambers, a conduit for conducting theremainder of said preheated air to the remainder of said evaporatorchambers, and means for conducting the first-named portion of saidpreheated air back to said exchanger from one of said certain evaporatorchambers for preheating incoming fresh air.

2. In a system for dehydrating a liquid product, a first evaporator, asecond evaporator, a heat exchanger, a heater, means for conductingfresh air through said exchanger for preheating the said air, means forconducting a portion of said air through said heater and through saidsecond evaporator, means for conducting said lastnamed air back to andthrough said exchanger for preheating said fresh air, means forconducting the remainder of said fresh air to and through said firstevaporator, means for spraying a liquid product into the air flowingthrough the first evaporator chamber and for spraying the concentrateinto the air flowing through the second evaporator.

3. In a system for dehydrating a liquid prodnot, a first evaporator, asecond evaporator, a heater, a heat exchanger, means for conducting acopious supply of fresh air through said exchanger to said firstevaporator and forcausing the same to pass through said evaporator in adownwardly moving spiral and then in an upwardly moving spiral, andmeans for conducting a portion of said fresh air passing through saidexchanger to said heater and said second evaporator and back throughsaid exchanger for heating air supplied to said first evaporator,

4. In a system for dehydrating a liquid product,

to said evaporator and the remainder through said heater to saiddehydrator, means for conducting said remainder of. drying medium fromsaid dehydrator back through said heat exchanger for preheating saiddrying medium, means for varying the proportionate amounts of saiddrying medium flowing to said evaporator and dehydrator, means forspraying a liquid 'product into said drying medium within saidevaporator, and means for praying the concentrate into the drying mediumin said dehydrator.

5. In a dehydrating system, a first evaporator, a second evaporator, adehydrator, an air heater, a heat exchanger, means for causing air toflow through said heater and for discharging the same into saiddehydrator in a spiral, means for conducting air from said dehydrator tothe sec-- ond evaporator and for discharging the same in a spiral intosaid last-named evaporator, means for conducting the air from saidsecond evaporator .through said heat exchanger, means for conductingfresh air through said heat exchanger for heating the same, means forcausing said last-named air to move spirally in said first evaporator,means for spraying a liquid product into the spirally moving air withinsaid first evaporator for concentrating said product, means for sprayingthe concentrated product into the spirally moving air within said secondevaporator for further concentrating said product, and means forspraying the concentrated product from said second evaporator into saidspirally moving air within said dehydrator for desiccating said product.

6. In a dehydrating system, a plurality of evaporator chambers, a heatexchanger, a heater, means for conducting fresh air through said heatexchanger for heating said air, means for dividing said fresh air, meansfor causing a portion of the divided air to fiow spirally downwardly andthen spirally upwardly within one of said chambers, means for causingthe other portion of said air to flow through said heater, through theremainder of said chambers and through said heat exchanger, means forspraying a liquid product into said one chamber, and means for sprayingthe concentrated liquid product from said last-named chamber into theremaining chambers.

7. In a system for dehydrating a liquid product, an initial evaporatingchamber, a heat exchanger, a second evaporating chamber, means forcausing a stream of fresh air to flow through said exchanger for heatingthe same, means for dividing said air, means for conducting a dividedportion of said air through said chamber, a heater, means for conductinganother portion of said air through said heater, through said secondevaporating chamber and back through said heat exchanger in heatexchange relation with said fresh air for heating the latter.

8. In a system for dehydrating fluid products which comprises an initialevaporator, an intermediate evaporator, a dehydrator, a heat exchanger,a heater, means for causing fresh air to flow through said heatexchanger, means for dividing the air flow from said heat exchanger,means for conducting a divided portion of said air to and from saidinitial evaporator and for causing the same to fiow spirally throughsaid initial evaporator, means for causing the remaining for heating thesame, means for portion of said air to flow through said heater mixingfresh air with said last-named heated air and for causing the same tomove spirally through said dehydrator, means for conducting the airmixture to said intermediate evaporator, means for conducting saidlast-named air to and through said heat exchanger for heating said freshair, means for spraying said fluid product into the stream of air insaid initial evaporator, means for spraying the concentrate into saidintermediate evaporator, and means for spraying the condensate from saidintermediate evaporator into the stream of air flowing through saiddehydrator.

9. In a system for reducin the moisture content of a fluid product whichcomprises a heat exchanger, an evaporator, means for conducting freshair through said heat exchanger for heating the same, means forconducting a portion only of said air discharged from said heatexchanger to said evaporator and for causing the same to flow throughsaid evaporator into the atmosphere, means for spraying said fluidproduct into the stream of air flowing through said evaporator forreducing the moisture content thereof, means for heating the remainderof said air discharged from said heat exchanger, means for utilizingsaid last-named air for reducing the moisture content of the concentratefrom said evaporator, and a conduit for conducting said last-named airback heat exchange relation with said fresh air for heating the latter.

10. In a system for concentrating and dehyof heated a1r withinsaid-snail Just prior to its a heat exchanger by to said heat exchangerin ucts, means including an drating a liquid-product, a first stageevaporator, a heat exchanger, a heater, a second stage evaporator, adehydrator, means for discharging a liquid product in the form of aspray into said first stage evaporator, means for conveying theconcentrate from said first stage evaporator to said second stageevaporator and the concentrate from the second stage evaporator to saiddehydrator, means for circulating air through said heat exchanger andfor passing a portion thereof through said heater and through saiddehydrator and said second stage evaporator for removing moisture fromsaid product, and means for conducting a portion only of the air passingthrough said heat exchanger through said first stage evaporator forreducing the moisture content of said liquid product. a

11. In a system for dehydrating liquid prodevaporator for concentratingthe product, means for concentrate from said first-named means, saidlast-named means comprising a dehydrator chamber, a snail above saiddehydrator chamber in communication with the chamber, a heater, a heatexchanger, and means for mixing a copious supply of fresh air with asmall supply discharge spirally into said dehydrator chamber, saidheated air having been preheated in said the residual heat remainin inthe air discharged from said dehydrator chamher and heated by saidheater.

JOSEPH M. HALL. V

dehydrating the

